You guys probably seen this but Magnus rejecting a 1.2M Euro payday and playing $10/25 abc poker at HCL while the chess championship is going on is just mind boggling. He must be very rich? Somewhere in the video he did say that playing classical chess is disenchanting.
Depends on your definition of rich. But, yeah, he is rich.
It seems the biggest reason for not defending his title is that he simply doesn't enjoy it - he ends up spending a very significant % of his career preparing for a match where a lot of it will be against a 3600+ computer engine.
Having said that, I bet if it was 10m to the winner he'd defend.